Dangerous liaisons: Jupiter, Venus, and Mercury

Above is this week's edition of an excellent feature from Sky & Telescope and PBS called SkyWeek, featuring Sky & Telescope Associate Editor Tony Flanders and excellent graphics and diagrams pointing the way to notable celestial events currently occurring in the sky.

This week's video focuses on the dramatic line of planets clearly visible in the evening sky just after sunset. The brightest of these is Venus, and not far behind Venus as it descends towards the west is Jupiter, also extremely bright but not so bright nor so large as Venus.

Jupiter and Venus are currently closing in on a spectacular conjunction, which will take place halfway through March of this year. This article from EarthSky explains why this particular conjunction of Jupiter and Venus will be particularly viewer-friendly: both planets remain visible after sunset much longer than they will during upcoming conjunctions in future years, when they will be close again but will be very low to the horizon in the west and set soon after the sun does.

The conditions which make the current dance of Venus and Jupiter so special are caused by the fact that Venus is approaching greatest evening elongation (or apparent distance from the sun as the evening star -- see this previous post for a diagram which explains the behavior of Venus as evening and morning star). Also, the ecliptic angle is currently very steep, as explained in the video above as well as in the EarthSky article.

The video also shows that Mercury will be visible just above the western horizon along the ecliptic path as the pencil-thin sliver of the new waxing crescent becomes visible after sunset on Wednesday. New moon occurs on Tuesday, February 21 as the sun "catches" the moon and then "passes" it up -- the young waxing crescent will then trail the sun by a greater and greater distance each day. It is most visible just after the sun goes down in the west, trailing by a short distance when it is barely a sliver, and by a larger and larger gap as its crescent grows. To see a discussion of the cause of the new moon and the waxing crescents visit this previous post.

Far behind the trio of Jupiter, Venus, and Mercury, you can find Mars rising in the east in the majestic constellation of Leo the Lion. Mars is currently in retrograde -- you can read some discussion of this phenomenon here and here, and see some diagrams that should help you locate it if you are unfamiliar with the location of this constellation here.

Numerous previous posts have discussed the very important work of Giorgio de Santillana and Hertha von Dechend in Hamlet's Mill, particularly their argument that the ancient myths (in addition to powerfully illuminating the human condition in their portrayal of the various personalities, weaknesses, and intrigues of the gods) also function as vessels for the preservation and transmission of detailed astronomical knowledge. See for example previous posts such as "Aristotle's 'ancient treasure'" as well as "Don't miss Saturn this month" (from May of 2011).

Based on this theory, we might expect conjunctions of Jupiter and Venus as well as approaches of Venus and Mercury to be enshrined in myth in some way (probably as a story about a sexual liaison), and that is indeed exactly what we do find (to see a previous post explaining how the famous myths regarding Ares and Aphrodite are almost certainly transmitters of astronomical events concerning Mars and Venus, see "Mars, Venus and the Pleiades").

Zeus is said to have pursued Aphrodite, who resisted his advances (Jupiter can be said to be pursuing Venus right now). He apparently is recorded as giving up the chase and not actually consummating the union, but spilling his seed in a furrow in lust over the voluptuous goddess. One look at the excellent EarthSky image of the upcoming March 2012 conjunction of Jupiter and Venus can give a hint as to what this myth is trying to convey:

Similarly, there are stories in which Hermes seduces Aphrodite. Note that he does not pursue her the way Zeus is described as doing: this is descriptive of the motion of the planets as well. Mercury is closer to the sun in our solar system, and hence is more closely tethered to the sun in our sky, remaining closer to the horizon after sunset than Venus can. Thus, Venus will actually be more accurately described as moving closer to Mercury (in other words, being "seduced by Hermes") than as being chased by him (the way Venus is currently being chased by Jupiter, which is outside of earth's orbit and thus can arc across the entire sky rather than staying near the rising or the setting sun the way that the interior planets Venus and Mercury must do).

The product of the union of Hermes and Aphrodite was a son named Hermaphroditos, according to some legends. His name is a combination of the names of his parents. As is evident by the continuing use of his name to this day to describe a person of dual sexual characteristics, ancient myths describe Hermaphroditos as possessing the characteristics of both male and female, either from birth or -- more commonly -- as the result of union with a nymph at a pool. After that incident, any man who bathed in the pool would also emerge half-woman.

The fact that we find stories about liaisons between Jupiter and Venus and between Mercury and Venus in the ancient myths, described in a manner which appears to be consistent with the actual behavior of the planets, lends powerful support to the argument that the myths were more than amazing literary achievements -- they preserved sophisticated scientific achievements as well.